Feeding an 8 Year Old JRT

I have adopted an 8 yr old female JRT (first time owner of this breed) that has become the center of our family. We love her immensely. She's my mothers little helper, my sweetheart, my fiance's buddy. I want to make sure we don't over feed her. She is healthy and active. I don't want to overfeed her, but she likes to eat late. We are working the clock back on that, but I want to keep her healthy and not make her overweight.

Thanks for any information and idea you may have.